Eleventh International Conference on Internal Friction and Ultrasonic Attenuation in Solids
J. Phys. IV France 06 (1996) C8-93-C8-96
High Temperature Internal Friction in Ni Ti AlloyV. Pelosin, F. Deborde and A. Rivière
Laboratoire de Mécanique et Physique des Matériaux, URA 863 du CNRS, ENSMA, BP. 109, 86960 Futuroscope cedex, France
Former internal friction studies concerning NiTi alloys are currently limited to the temperature range 300 K-400 K relative to the martensitic transition. This paper describes results obtained by isothermal mechanical spectroscopy between 400 K and 1050 K with a sample in austenitic phase after different thermomechanical treatments : cold rolled, deformed by tension, submitted to successive transition cycles or annealed at high temperature. Two relaxation peaks superimposed to a low frequency (i.e. high temperature) background were found. For the first one (520 K at 1 Hz) both, the variation of the relaxation strength with the measurement temperatures and the relaxation parameters (Ea = 1.35 eV and τo = 2.5x10-14 s) correspond to a Zener relaxation. The high temperature peak (870 K at 1 Hz) was associated with a relaxation due to dislocation segment motion.
© EDP Sciences 1996